1.2 PAGs

1.1: Determining g using light gates (method):

-Set up apparatus

-Clamp light gates as close to the electromagnet as possible

-Connect light gates to a datalogger

-The height between the light gates (h) is 0.75m, measured with a metre ruler

-Turn on electromagnet and attach ball bearing

-Switch off electromagnet

-Record the time taken for the ball bearing to fall between the light gates measured by datalogger

-Reduce h by 0.05m by moving the lower light gate upwards

-Repeat thesteps until h = 0.25m

-Repeat experiment twice more to find mean values of t for each value of h

1.1: Determining g (calculations):

Using s = ut + (at^2)/2:

-Plot a graph of 2h against t^2

-Draw line of best fit

-Take gradient to find g (2h/t^2 = g)

1.1: Determining g using tennis ball (method):

-Using the metre ruler, measure a height (h) of 1.0m

-Place soft pad at the bottom of the ruler

-Hold the tennis ball so the bottom half is at the 1.0m mark

-Release the ball and simultaneously switch on the stopwatch

-Switch off the stopwatch as soon as the ball hits the soft pad

-Record the time taken for the ball to fall from stopwatch

-Reduce h by 0.05m

-Repeat the steps until h = 0.50m

-Repeat the experiment twice more to find mean values of t for each value of height

1.2: Investigating terminal velocity (method):

-Wrap elastic bands around the tube of viscous liquid at set intervals measured by a ruler

-Drop the ball into the tube and record the ball falling at eye-level with the camera

-Find the time it reaches each band at

-Repeat the experiment four times to reduce the effect of random errors

-Use the magnet to remove the all bearing from the bottom of the tube

1.2: Investigating terminal velocity (calculations):

-Use v = s/t to find the average velocity of the bearing between each set of bands

-Plot a graph of velocity against time

-The velocity the graph tends to is the terminal velocity

1.3: Investigating initial speed and stopping distance (method):

-A vehicle is modelled by the block of wood which is pushed and decelerates due to friction with the surface it moves on

-Glue the 10x10cm interruptor card to the side of the block of wood so it passes through the light gate as it moves

-Set up the light gate such that it records the time taken for the card to pass through it

-Record the starting position of the block and position the gate 2cm after this point

-Push the block and record the position at which it stops

-Record the time for the card to pass through the gate and the corresponding distance between the light gate and stopping point

-Repeat the experiment for a range of starting velocities

-Make sure the block is pushed on the same surface each repetition so the frictional forces stay constant

1.3: Investigating initial speed and stopping distance (calculations):

-Calculate the starting velocity from the time values recorded (v = 0.10/t)

-Plot a graph of stopping distance against starting velocity squared

-This is a straight line through the origin as E = (mv^2)/2 and all the energy is lost due to friction

-(mv^2)/2 = force x stopping distance

-This shows that v^2 ∝ stopping distance

2.1: Determining the Young Modulus of a metal (method):

-Measure and record the diameter of the wire in 3 different places using a micrometer

-Set up the apparatus

-Attach the metre ruler to the workbench so that it is parallel to the wire, face its lower end to the G-clamp

-Place a marker on the wire at 0cm on the ruler

-Measure the length of wire from the blocks of wood holding the wire to the marker when it is taut

-Attach a mass to the wire and record the total mass attached to the end of the wire in kg

-The wire stretches, record the new position of the marker

-Add another 100g mass and record the position

-Repeat the steps until a full dataset is attained

-Wear eye protection, as if the wire snaps and flies out it could lash your eye

-Put cushioning under the masses in case the wire snaps so they won't hit people's feet if they fall

2.1: Determining the Young Modulus of a metal (calculations):

-Find the mean diameter of the wire and calculate the average cross-sectional area using A = (πd^2)/4

-Using F = mg calculate the force exerted on the wire for each mass and record these values in a table

-Calculate the wire's extension by finding the difference between the marker's initial and final position for each mass

-Find the stress on the wire for each mass (σ = F/A)

-Find the strain on the wire for each mass (ϵ = ΔL/L)

-Plot a graph of stress against strain

-The line of best fit is a straight line going through the origin

-The gradient of the line is equal to the Young Modulus of copper

2.2: Investigating springs in series and in parallel (method):

Series:

-Record the original length (L) of the spring(s) and the number of springs in the series (n)

-Attach the mass and record the new length of the springs

-Repeat for different values of n

Parallel:

-Record the original length of the springs in parallel

-Attach the mass and record the new length of the springs

-Repeat for different numbers of springs in parallel

Safety and notes:

-Do not exert too high a force on the springs as the springs will deform and become permanently extended

-The apparatus may also break causing the masses to fall and potentially cause injury

-Don't let springs recoil too quickly as they can snap on fingers and cause cuts

-Wear eye protection

-Always measure the spring's position from the same point marked with a marker

2.2: Investigating springs in series and in parallel (calculations):

-Work out the extension for each spring combination by finding the difference between the new length and the original length

-Find the spring constant of the combination (k = F/e = mg/e)

Series:

-Check the spring constant using the equation 1/k = 1/k(1) + 1/k(2) + ...

Parallel:

-Check the spring constant using the equation k = k(1) + k(2) + ...

2.3: Investigating a property of plastic (method):

-Using the guillotine, slice the plastic bag both lengthways and sideways to test its properties in each plane

-Seperate these sections so that they don't get mixed

-Holepunch one end of each strip to create a hole to hang the masses from

-Attach the strip to a clamp stand and measure its original length from where it is attached to the clamp stant to the hole where the masses are attached

Loading:

-Attach a 100g mass to the strip of plastic and measure its new length

-Repeat this process, measuring the new length until there are at least 10 readings of extension for a given mass

-Apply this method to the other strips, recording which orientation they came from

Unloading:

-For strips that do not break, rather than beginning a new strip, remove the masses one by one

-Record the new length after each removal

Safety and notes:

-Using a bulldog clip wound around the bag allows more even distribution of the weight of the masses

-Using spreadsheet software can quickly calculate the forces and extensions

-Read the ruler at eye level to avoid parallax error

-Cushion the floor below the masses and be wary of them falling

-Be careful when using a guillotine

2.3: Investigating a property of plastic (calculations):

-Plot a graph of force against extension

This will show the properties of the plastic, for instance:

-Limit of proportionality: the point after which Hooke's law is no longer obeyed

-Elastic limit: if you increase the force applied beyond this, the material will deform plastically

-Breaking stress is the value of stress at which the material will break apart depending on its conditions

-The area between loading and offloading lines represent the work done to permanently deform the material

3.1: Determination of resistivity of a wire using a micrometer, ammeter and voltmeter (method):

-Measure the diameter of the constantan wire at 3 points along its length

-Set up the apparatus

-Adjust the length l to 10cm using the crocodile clips and metre ruler

-Read and record the current (I) on the ammeter and voltage (V) on the voltmeter

-Calculate the resistance (R) using R = V/I and record this value

-Switch the circuit off between readings to prevent heating of components which could affect their resistance

-Increase l by 10cm and repeat the steps until l = 80cm

-Repeat the experiment twice more and calculate the mean resistance for each length

Safety and notes:

-Disconnect the crocodile clips in between measurements to avoid overheating and causing burns if touched, it may also increase the resistance of the wire

-If the current rises too high, reduce the voltage using the variable power supply

-If the wire is taut, safety goggles should be worn in case it snaps

3.1: Determination of resistivity of a wire using a micrometer, ammeter and voltmeter (calculations):

-Calculate the cross-sectional area of the wire

-Plot a graph of the mean resistance against length and draw a line of best fit

-The gradient will be equal to ρ/A

-Hence ρ is found by multiplying the gradient by the cross sectional area

3.2: Investigating electrical characteristics for a range of ohmic and non-ohmic components (method):

-Set up the apparatus such that the components under investigation can be swapped out

-Vary the voltage across the component by changing the resistance of the variable resistor using a wide range of voltages

-For each voltage, record the current 3 times

-Make sure to switch off the circuit in between readings to prevent heating of components

-Repeat for all three components

Safety and notes:

-The components will get hot at higher voltages so be careful when handling them and disconnect the circuit between readings

-Do not put non-insulated metal into the plug sockets to reduce the risk of electrocution

-The voltmeter does not have an infinite resistance and the ammeter will not have zero resistance, therefore this is a source of error

-The equipment used and the temperature of the area should be controlled

-To reduce uncertainty test a wide range of voltages and use ammeters and voltmeters with greater resolution

3.2: Investigating electrical characteristics for a range of ohmic and non-ohmic components (calculations):

-Plot a graph of mean current against voltage for each component

-Compare the shapes of each graph and consider the reasons behind the differences for the filament lamp, the copper block and the diode

3.3: Determining the internal resistance and maximum power of a cell (method):

-Set up the apparatus

-Set the variable resistor to its maximum value

-Close the switch and record voltage from the voltmeter and current from the ammeter

-Open the switch between readings to prevent heating of the variable resistor

-Decrease the resistance of the variable resistor and repeat this obtaining paris of readings of V and I over the widest possible range

Safety and notes:

-Another resistor can be included in series with the other to avoid high currents which could make the wires and resistor hot

-Only close the switch for as long as it takes to get a pair of readings

-Use fairly new batteries/cells because the emf and internal resistance of run down batteries can vary during the experiment

-Check there is no systematic error from the ammeter and voltmeter by calibrating them beforehand

3.3: Determining the internal resistance and maximum power of a cell (calculations):

-ϵ = I(R+r) = V + Ir

-V = -Ir + ϵ (y = mx + c)

-Plot a graph of V against I and draw a line of best fit

-The y-intercept will be the emf of the cell and the gradient will be the negative internal resistance

4.1: Investigating combinations of resistors (method + calculations):

-Check the given resistance of the resistors is accurate using an ohmmeter

-Record and use their actual resistances

-Design at least three circuits of resistors connected to a cell and voltmeter(s) in different configurations

-Calculate the theoretical total resistance in each of the circuits designed

-Next, record the voltage on each voltmeter and find this voltage as a percentage of the 5V supply

-Find the resistance of each resistor as a percentage of the total resistance of its circuit

-Compare the corresponding voltmeter percentages and resistor percentages

-They should be approximately equal

Safety and notes:

-Using a 5V supply minimises the risk of electrocution and heating components

-Calibrate the voltmeters before connecting them to avoid systematic error

4.2: Investigating circuits with more than one source of emf (method):

-Set up the first circuit with two cells facing the same way in series with a resistor

-Record the voltage across the resistor

-Set up the second circuit with two cells facing the same way in parallel with a resistor

-Record the voltage across the resistor

-Swap at least one of the cells in the series circuit so that they are of different voltages and record the reading on the voltmeter again

Safety and notes:

-Do not connect cells of two different voltages in parallel, especially if large as one will discharge into the other causing wires to be burnt, sparks when connecting to other cells and overheating

-Do not use high voltage batteries to reduce risk of electrocution

-The resistor may get hot so do not touch it

4.2: Investigating circuits with more than one source of emf (calculations):

-Calculate the expected combined potential difference for each cell combination using rules about cells in series and parallel

-Compare the theoretical combined potential difference and compare it to the actual, discuss the reasons behind this difference, e.g. internal resistance

4.3: Using non-ohmic devices as sensors (method):

LDR:

-Set up apparatus

-Make the area surrounding the circuit as dark as possible

-Record the value of the light intensity using the digital light sensor

-Record the voltage across the resistor for this light intensity

-Using the lamp with a dimmer switch, increase the light intensity slightly and record the new intensity and voltage

-Repeat this process until the light intensity cannot be increased further

Thermistor:

The method for using the thermistor to find an unnown temperature is similar to the one above but with certain alterations:

-The LDR in the circuit must be replaced with a waterproof thermistor

-Rather than light intensity being altered it is the temperature that is altered

-The thermistor is placed in boiling water from the kettle

-Record the voltage across the resistor as before

-Take readings every five degrees using ice to lower the temperature

-Plot a graph of voltage agaisnt temperature and use a calibration curve to find an unknown temperature

Safety:

-Be careful not to be scalded by boiling water by not letting it splash

-Do not look directly into the lamp

-Be careful not to trip when the room is dark

-Take as many readings as possible over a wide range to increase the accuracy of the calibration curve

-The resistance of the LDR and thermistor decreases as light intensity and temperature increases respectively

-The experiment uses a potential divider circuit

4.3: Using non-ohmic devices as sensors (calculations):

-Plot a graph of voltage across the resistor against light intensity (or temperature) and draw a line of best fit

-This can be used as the calibration curve

-Move the circuit to an area of unknown light intensity and record the voltage across the resistor

-Using the calibration curve, find the corresponding light intensity to this voltage

5.1: Determining the wavelength of light using a diffraction grating (method):

-Shine the laser through the diffraction grating onto the screen

-Measure the distance between the central fringe and the one beside it with a ruler (1st order)

-Measure the distance between the grating and the screen with a ruler

Safety and notes:

-Don't point the laser at your eye

-2nd and 3rd order measurements and the average of these values can be used to find the mean wavelength

5.1: Determining the wavelength of light using a diffraction grating (calculations):

-The formula associated with diffraction gratings is:

λ = ax/D

Where a is the slit seperation, x is the fringe seperation and D is the distance between the grating and the screen

-Substitute the values recorded into the equation to find the wavelength of the laser

5.2: Determining the speed of sound by formation of stationary waves in a resonance tube (method):

-Fill the resonance tube halfway with water

-Hit the tuning fork of a known frequency with a hammer and hold it above the tube

-Lower the water level until the intensity of the sound is amplified when resonance is heard and mark the water level

-Then, lower the water until the next point of resonance is heard and mark the water level

-Repeat this as far as possible

-Resonance occurs when the open tube length is:

λ/4, 3λ/4, 5λ/4...

Safety and notes:

-Don't let the tuning fork touch the resonance tube as the vibrations can break the tube

-The open end acts as the antinode but the real antinode is about 0.6r from the end (r is the tube radius)

-This correction can be applied to make the values more accurate

5.2: Determining the speed of sound by formation of stationary waves in a resonance tube (calulations):

-Using the length (L) between two markers (L = λ/2) the wavelength is found (λ = 2L)

-The mean wavelength can be found by the mean length between markers

-The mean wavelength is multiplied by the frequency of the tuning fork to find the speed of sound for the present conditions of the room

5.3: Determining frequency and amplitude of a wave with an oscilloscope (method):

-Connect the microphone to the oscilloscope input and play one note on the instrument into the microphone

-Use the oscilloscope to determine both the frequency and amplitude of the signal

-Compare these frequency and amplitude values to database values to determine the note played and whether it is in tune

5.3: Determining frequency and amplitude of a wave with an oscilloscope (oscilloscope reading):

-Oscilloscopes show the variation of voltage with time

-For an alternating current, the trace will show a repeating sinusoidal waveform which shows the variation of output voltage with time

-For a DC current, a straight line parallel to the x-axis will be shown

-The axes can be adjusted to make measurements easier

-In order to take measurements, count the number of divisions and multiply them by either the volts per division or time per division

5.4: Determining wavelength using diffraction from a CD (method):

-Measure the distance (r) from the centre of the CD to the edge of the CD

-Choose a colour of light you would like to calculate the wavelength for

-Move the CD away from your eye until the red light is on the edge of the CD

-Measure the distance

-Repeat for other colours of light

Safety and notes:

-Do not stare at the lamp for extended time periods

-The lamp may get hot

5.4: Determining wavelength using diffraction from a CD (calculations):

-Calculate the angle of diffraction using trig

-By using a variety of colours of light and their diffraction angles calculate the ratio between the wavelengths, e.g.:

λ(red)/λ(green) = sin(θ(red))/sin(θ(green))

-Compare these ratios with accepted values and calculate the uncertainty

6.1: Determining the Planck Constant using LEDs (method):

-Connect an LED with a voltmeter across it to a cell in series with an ammeter

-Find the wavelength of light the LED is emitting from datasets or its packaging

-Find the threshold voltage of the LED by recording the potential difference across it at which it lights up (where current flows)

-Find the threshold voltage for a range of LEDs of different wavelengths and record these in a table of wavelength against threshold voltage

Safety and notes:

-Use a wide range of LEDs and take repeats to draw the most accurate line of best fit

-Make sure the wavelength is in metres and the voltage in volts

6.1: Determining the Planck Constant using LEDs (calculations):

-Plot a graph of threshold voltage (V) against 1/wavelength (1/λ)

-Calculate the gradient of the line of best fit

-The energy of the photons emitted by the LED have energy (E) = hf = hc/λ = eV, where e is the charge of an electron

-hc/λ = eV

-hc/e = Vλ

-The gradient is Vλ, so h is found by finding the product of e/c and the gradient

6.2: Experiments with light (method):

Semi-circular block:

-Place the semi-circular block on top of the protractor with the centre of its diameter alligned with 0 degrees on the protractor

-Direct the ray towards this 0 degree point from a 180 degree angle and trace the ray entering the block and leaving with a pencil

-Repeat this, moving the ray around every 10 degrees

-Record the angle at which the angle of refraction is 90 degrees (critical angle)

-Increase the angle further and observe that it doesn't leave the block

Rectangular block:

-Place the block on white paper and trace around it to mark its position

-The straight part of the protractor should be against the long side of the block

-Mark a point on the longer edge about 1cm from the corner (this is the incident ray target)

-Aim the beam normal to the block and trace the entry and exit ray

-Rotate the beam 10 degrees each time, still entering the block at the same marking and record each path

-For each position, measure the angle of incidence and the angle of refraction

Safety and notes:

-Using a laser gives more defined rays so there is less uncertainty with the trace line

-Do not shine the light from the ray box in the eyes

-Do not shine the light from the laser in the eyes

6.2: Experiments with light (calculations):

-The refractive index of the rectangular block, n = sin(i)/sin(r) where i is the incident angle and r is the refraction angle

-The refractive index of the semi-circular block is n = 1/sin(c) where c is the critical angle

6.2: Young's Double Slit Experiment (method):

-Shine the laser through the double slit so each slit acts as a coherent point source

-Observe the pattern of light and dark fringes on the screen

-Mark the centre of each bright spot, then turn the laser off and measure the distance of at least 4 fringe spacings

-Measure the distance from the slits to the screen (D) and record the distance between the slits (a)

6.2: Young's Double Slit Experiment (calculations):

-Find the fringe spacing (x) by dividing the distance of n fringe spacings by n

-Rearrange the double slit equation to make λ the subject: λ = ax/D

-Substitute the values in to find λ

6.3: Experiments with polarisation (method):

Light:

-For light, hold a polarising filter up to eye level

-Place another filter behind it and rotate it

-Observe that when the filters are perpendicular, no light gets through

Microwaves:

-For microwaves, place a vertically aligned metal grille between the transmitter, which transmits vertically polarised microwaves, and the detector

-Make sure the detector is working and the waves are vertically aligned by turning on the transmitter and check the detector with and without the grille

-Place a horizontally aligned grille behind the first and observe whether the detector records any microwaves

Safety:

-Microwaves can cause burns if they are too intense

-Do not stand in front of the transmitter when it is on

-Do not look directly into a bright light as it damages eyesight

-Only transverse waves can be polarised

-Reflected light is partially polarised as the light perpendicular to the surface is flipped around and destructively interferes with itself when reflected

7.1: Observing radioactive decay's random nature (method):

-Set up the clamp stand and attach the GM tube to it

-Connect the GM tube to the counter

-Switch on the counter for 30 seconds without a source

-Record the background count

-Remove the source from its storage box using long-handled tongs

-Place it 0.1m away from the GM tube in the source holder

-Switch on the counter and take readings of count for 10 seconds every 30 seconds for 5 minutes

-When recording readings, subtract the background count from the recorded value to produce a corrected count rate

- Repeat this procedure twice more with a new source, waiting 5 minutes between repeats

-Find the average count for each reading

Safety and notes:

-Ionising radiation can be incredibly dangerous

-Never directly handle the source, use tongs instead

-Store the source in a lead-lined container

-Never point the source at others

-Keep the source as far away as possible from yourself and others

-The decay follows an exponential decay curve for sources with short half-lives

-For sources with longer half-lives, the values of count rate appear to be completely random

7.1: Observing radioactive decay's random nature (calculations):

-Draw a table of corrected count rate against time

-Plot a graph of corrected count rate against time and draw a line of best fit, which will be a curve

-You will see that the decay is exponential

-Find the half life of the sample using the graph

7.2: Investigating the absorption of α-particles, β-particles and γ-rays by appropriate materials (method):

-Connect the counter to the GM tube

-Switch on the counter for at least five minutes

-Record the background count rate

-Using the tongs, place the source about 5cm from the geiger counter

-Measure the count rate after 5 minutes

-Record the corrected count rate

-Repeat the experiment with the same source, blocking the GM tube with paper, then aluminium, then lead

-Repeat the experiment with a different source

Safety and notes:

-Ionising radiation can be incredibly dangerous

-Never directly handle the source, use tongs

-Store the source in a lead-lined container when not in use

-Never point the source at yourself or others

-Keep the source far from yourself and others

7.2: Investigating the absorption of α-particles, β-particles and γ-rays by appropriate materials (calculations):

-If the count rate significantly decreases when the GM tube is blocked with paper, the source gives out mainly α-particles

-If the count rate significantly decreases when the GM tube is blocked with aluminium, the source gives out mainly β-particles

-If the count rate significantly decreases when the GM tube is blocked with lead, the source gives out mainly γ-rays

7.3: Determine half-life using an ionisation chamber (method):

-Set up the ionisation chamber, connecting it to the DC voltage source and ammeter

-Remove the radioactive source from its storage box and place it in its holder in front of the ionisation chamber

-Immediately start the stopwatch

-Record the ionisation current every 10 seconds for 3 minutes

-Repeat this procedure twice more with a new source after waiting for at least 5 minutes between repeats

-Find the average current for each reading

Safety and notes:

-Ionising radiation can be incredibly dangerous

-Never directly handle the source, use tongs

-Store the source in a lead-lined container when not in use

-Never point the source at yourself or others

-Keep the source far from yourself and others

7.3: Determine half-life using an ionisation chamber (calculations):

-Draw a graph of ionisation current agaisnt time

-Draw a line of best fit, which will be a curve

-The decay is exponential

-Find the half-life of the sample

8.1: Estimating the value for absolute zero from volume (method):

Volume:

-Attach the ruler to the capillary tubes using 2 elastic bands so that the 0cm mark is at the very start of the length of hte air sample

-Boil water using the kettle, leaving it to cool slightly before pouring it carefully into the large beaker

-Place the capillary tube into the beaker with the open end facing upwards

-Measure the temperature of the water using the thermometer, making sure to stir the water with the thermometer beforehand

-Record this value

-Measure the length of the air sample without removing the capillary tube from the beaker

-Decrease the temperature of the water by 5 degrees by adding a small amount of cold water/ice

-Again, measure the temperature and length of the air sample

-Repeat the above steps until the water reaches room temperature

Safety and notes:

-Be careful when pouring boiling water to avoid scalding yourself

-Take care when using glassware to avoid breaking it and touching sharp shards of glass

8.1: Estimating the value for absolute zero from pressure (method):

-Place the bung into the neck of the flask making sure it sits tightly so that it does not fall out

-Attach the connective tubing to the bourdon gauge, again making sure it fits tightly

-Place the flask into the large beaker

-Boil the water using the kettle, leaving it to cool slightly before carefully pouring it into the large beaker until it reachers the bung in the flask

-Meaure the temperature of the water using the thermometer, making sure to stir the water beforehand

-Record this value

-Record the value of the pressure on the bourdon gauge

-Decrease the temperature of the water by 5 degrees by adding a small amount of cold water/ice

-Again, measure the temperature and pressure of the air in the flask

-Repeat the above steps until the water reaches room temperature

Safety and notes:

-Be careful when pouring boiling water to avoid scalding yourself

-Take care when using glassware to avoid breaking it and touching sharp shards of glass

8.1: Estimating the value for absolute zero (calculations):

-Plot a graph of pressure or volume against temperature and draw a line of best fit

-The line of best fit will be a straight-line cutting the y-axis

-It will have the equation y = mθ + c where y is pressure or volume, m is the gradient of the line (nR from pV = nRT) and c is the y-intercept

-The line equation can be found by substituting the values from the graph into the general equation

-At absolute zero the pressure or volume of the gas sample is zero

-Absolute zero is found by making the line equation equal to zero and rearranging for θ

8.2: Investigating the relationship between pressure and volume (method):

-Take the plunger out of the syringe

-Measure the syringe's internal diameter using Vernier callipers and record it

-Place the plunger back into the syringe

-Draw 5cm^3 of air

-Without moving the plunger, place the tubing over the nozzle and pinch it shut with pinch clips

-Set up the clamp and attach the syringe so that the plunger is downwards

-Attach the string to the end of the plunger, leaving a loop

-Attach the 100g mass holder to the loop

-Record the volume recorded by the syringe

-Add a 100g mass to the holder and record the volume

-Repeat the above step until the total mass is 1kg

-Repeat the procedure twice more and calculate the mean values of volume

Safety and notes:

-Be careful when handling masses - if dropped they can cause injury

-If the clamp stand is unstable, a counterweight placed on the base or a G clamp can prevent it from falling over

8.2: Investigating the relationship between pressure and volume (calculation):

-Calculate the cross-sectional area of the syringe in metres: A = πd^2/4

-Calculate the force exerted by each of the recorded masses by calculating their weight: W = mg

-Using the equation P = F/A, calculate the total pressure exerted on the gas at each value of force

-Total pressure is the sum of the pressure of the air sample and atmospheric pressure, therefore atmospheric pressure must be subtracted from the calculated values

-Plot a graph of 1/V against the pressure of the air sample and draw a line of best fit

-Line of best fit should form a straight line through the origin

8.3: Estimating the work done by a gas as its temperature increases (method):

-Measure the internal diameter of the capillary tube using vernier callipers

-Attach the 30cm ruler to the capillary tubes using 2 elastic bands so that the 0cm mark is at the very start of the air sample

-Boil water using a kettle, leaving it to cool slightly before pouring it into the large beaker

-Place the capillary tube into the beaker, with the open end facing upwards

-Measure the temperature of the water using the thermometer, making sure to stir the water beforehand

-Record this value

-Measure the length of the air sample without removing the capillary tube from the beaker

-Decrease the temperature of the water by 5 degrees C by adding a small amount of ice

-Again, measure the temperature and length of the air sample

-Repeat the above steps until the water reaches room temperature

Safety and notes:

-Sulphuric acid is corrosive and may irritate the skin or cause damage to the eyes

-Safety goggles must be worn and the capillary tube must be handled carefully

-Boiling water may cause burns so care should be taken when handling it

8.3: Estimating the work done by a gas as its temperature increases (calculations):

-Calculate the cross sectional area of the capillary tube: A = πd^2/4

-Calculate the volume of the air sample at each length by multiplying each length by the cross-sectional area

-Plot a graph of volume agaisnt temperature and draw a line of best fit

-Line should be straight

-The air inside the tube is allowed to expand freely meaning it is under atmospheric pressure

-As the pressure is constant, the work done is calculated thus: E = pΔV

-The temperature and volume are directly proportional, therefore as temperature increases, the work done increases

9.1: Investigating the charge and the discharge of a capacitor (method):

Charging:

-Set up a circuit with a cell, switch, resistor, ammeter and capacitor in series

-Connect the voltmeter across the capacitor

-Close the switch to charge the capaitor

-Record the voltage and current at time t = 0 and at 5s intervals as the capacitor charges until 120s have passed

-Repeat the experiment twice more and record the voltage and current for each time again

Discharging:

-Set up a circuit with a cell, capacitor, voltmeter and resistor in parallel

-Connect a two pole switch to the capacitor such that it charges from the cell in position A and discharges into the resistor in position B

-Set the switch to the A position and allow the capacitor to fully charge

-Move the switch to the B position and start the stopwatch

-Observe and record the voltage reading at time t = 0 and at 5s intervals as the capacitor discharges until about 120s have passed

-Repeat the experiment twice more and obtain the average V at each t

-The experiment may be repeated with different resistors and capacitors to see how the time constant varies

Safety and notes:

-Ensure the capacitor is connected with the correct polarity and that its voltage rating exceeds the voltage of the battery

-This prevents it from exploding and releasing harmful chemicals

9.1: Investigating the charge and the discharge of a capacitor (calculations):

Charging:

-Calculate the mean voltage and mean current for each time

-Plot a graph of voltage against time, showing an exponential growth curve with the equation:

V = V0(1 - e^(-t/RC))

-Plot a graph of current against time, showing an exponential decay with the equation:

I = I0e^(-t/RC)

Discharging:

-Calculate the natural logarithm of V at each t and tabulate this

-Plot a graph of ln(V) against t and draw a line of best fit

-The line equation is ln(V) = ln(V0) - t/RC

9.2: Investigating capacitors in series and parallel combinations using ammeters and voltmeters (method):

Part 1:

-Set up a circuit with a cell, switch, variable resistor, ammeter and capacitor in series

-Connect a voltmeter across the capacitor in parallel

-Close the switch and adjust the variable resistor to keep the current constant for as long as possible

-Record the value of the constant current as well as the potential difference and the time since closing the switch in a table

Part 2:

-Modify the circuit from part 1 by connecting an identical capacitor across the first in parallel

-Repeat the procedure from part 1

Part 3:

-Modify the circuit from part 1 by connecting an identical capacitor to the first in series

-Repeat the procedure from part 1

Safety and notes:

-Using a data logger to record voltage and current will be more efficient and convenient as the data logger can calculate the charge in real time and plot a graph of charge against voltage

-It will be impossible to keep the current constant once the capacitor is fully charged, exclude values for which current is inconstant

-Check before closing the switch that there is no systematic error in the voltmeter or ammeter

9.2: Investigating capacitors in series and parallel combinations using ammeters and voltmeters (calculations):

Part 1:

-Calculate the charge across the capacitor by multiplying the fixed current by the time in seconds since the switch was closed

-Plot a graph of charge in coulombs against voltage in volts and draw a line of best fit

-Find the gradient of the line - this is the capacitance of the capacitor in farads

Part 2:

-Repeat the steps for part 1 using the data from part 2

-The capacitance of the circuit should be double that of part 1

Part 3:

-Repeat the steps for part 1 using the data from part 3

-The capacitance of the circuit should be half that of part 1

9.3: Investigating the factors affecting capacitance (method):

-Set up the clamp stand and attach one of the aluminium plates to it, using the wooden blocks to insulate it and making sure it is parallel to the work bench

-Place the large wooden block below the plate and place the second plate upon it, making sure they are perfectly aligned

-Using the metre ruler, make sure the distance between the plates is 10cm and keep this constant throughout the experiment

-Measure the length and width by which the plates overlap using the metre ruler

-Using crocodile clips and leads connect the two plates to a multimeter to record the capacitance

-Disconnect the circuit and move the large wooden block and plate atop it to the right by 5cm, making sure the entire width of the plates still overlap

-Measure the new length by which the plates overlap

-Reconnect the circuit and measure the capacitance

-Repeat the last steps until you have at least 7 readings

-Repeat the entire procedure twice more and find mean values of capacitance for each reading

Safety and notes:

-Uncalibrated multimeters may cause a zero error

-Other factors may be investigated

-The distance between the plates can be changed

-The permittivity can be changed by using different insulators between the plates

9.3: Investigating the factors affecting capacitance (calculations):

-Find the area of overlap by multiplying each length by the width of the plates

-Plot a graph of capacitance against the area of overlap and draw a line of best fit

-The line should be a straight line passing through the origin

-It has line equation C = Aε0εr/d

-Air has εr = 1

-The value of ε0 can be found by multiplying the gradient of the line by the distance between the plates

10.1: Investigate the factors affecting simple harmonic motion with a simple pendulum (method):

-Attach the ball bearing to the string and attach this to the clamp stand

-Adjust the length l, which is from where the string is attached to the clamp stand to the centre of the ball bearing, until it is 1.0m using the metre ruler

-Wait until the pendulum bob stops moving completely, then place the ficidual marker directly underneath the bob

-Pull the pendulum bob slightly to the side and let go so that it is oscillating with a small amplitude in a straight line

-As the pendulum passes the ficidual marker, start the stopwatch and count the time taken to complete 10 full oscillations

-Take two more readings of the time period for 10 oscillations and calculate a mean

-Reduce the length l by 10cm and repeat the last 3 steps of the procedure

-Repeat the last step until the length l is 0.2m

Safety and notes:

-To reduce the uncertainty further, a light gate attached to a datalogger can be used to record a period of 10 oscillations

-The angle by which you pull the pendulum bob must be less than 10 degrees, otherwise it will not undergo SHM

10.1: Investigate the factors affecting simple harmonic motion with a simple pendulum (calculations):

-Divide the mean values of time period at each length by 10 to get the time period of a single oscillation

-Draw a table of values of T^2 against l

-Plot a graph of T^2 against l

-The line of best fit should be a straight line through the origin

-The gradient is 4π^2/g

-Multiplying the gradient by 1/4π^2 will give a value of g

10.1: Investigate the factors affecting simple harmonic motion with a mass-spring system (method):

-Attach the spring to the clamp stand and attach the mass holder to the spring

-Wait until the spring stops moving completely, then place the fiducial marker at the bottom of the mass holder using the metre ruler to align it perfectly

-Pull the spring down slightly and let it go so that it is oscillating with a small amplitude and in a straight line

-As the bottom of the mass holder passes the fiducial marker, start the stopwatch and count the time taken for 10 full oscillations

-Take two more readings of the time period for 10 oscillations and calculate a mean

-Add a 100g mass to the mass holder and repeat the last 3 steps of the procedure

-Repeat the last step until the total mass is 800g (including the mass holder which is 100g)

Safety and notes:

-Be careful when handling the masses - dropping them could cause injury

-If the clamp stand is unstable, a counterweight placed on the base of the clamp stand can prevent it from falling over

-Alternatively, the stand can be clamped to the work bench with a G-clamp

-Wear eye protection when using springs

10.1: Investigate the factors affecting simple harmonic motion with a mass-spring system (calculations):

-Divide the mean values of time period at each length by 10 to get the time period of a single oscillation

-Draw a table of values of T^2 against m

-Plot a graph of T^2 against m

-The line of best fit should be a straight line through the origin

-The gradient is 4π^2/k

-Multiplying the gradient by 1/4π^2 will give a value of k

10.2: Observing damped oscillations (method):

-Attach the spring to the clamp stand and attach the 500g mass holder to the spring

-Wait until the spring stops moving completely

-Place the fiducial marker at the very bottom of the mass holder

-Attach the 15cm rulers either side of the fiducial marker using rubber bands

-Pull the spring down slightly and let it go so that it is oscillating with a small amplitude in a straight line

-As the bottom of the mass holder passes the fiducial marker, start the stopwatch and count the time taken for it to complete 10 full oscillations

-Once again, pull down the spring and let it go, recording the amplitude it is pulled to

-Measure the maximum amplitude of the spring at the start of every oscillation for at least 10 oscillations

-Repeat the above two steps twice and calculate the mean values of maximum amplitude at each oscillation

-Repeat the above procedure but this time using the 400g mass holder and the damping card wedged between the mass holder and a 100g mass

Safety and notes:

-Be careful when handling masses - dropping them may cause injury

-If the clamp stand is unstable, a counterweight placed on the base of the clamp stand can be used to prevent it from falling over

-Wear eye protection when using springs

10.2: Observing damped oscillations (calculations):

-Divide the collected values of time period by 10 to get the time period for a single oscillation

-Calculate the frequency of the oscillations when the damping card is and is not present using f = 1/T

-Plot a graph of the maximum amplitude against the number of oscillations for both systems and draw a line of best fit

-The resulting curve should be a characteristic exponential decay

11.1: Techniques and procedures used to investigate transformers (method):

-Put the 2C cores together and wrap 5 turns round the primary coil and 10 round the secondary

-Connect a voltmeter across both coils and connect the primary coil to a low AC supply

-Turn on the AC supply and record the voltage across each coil

-Keeping the same AC supply repeat the experiment with different turn ratios

-Now investigate the relationship between current and voltage for the number of turns of a coil

-Add a variable resistor to the primary coil circuit and an ammeter to both circuits

-Keeping the number of turns constant, turn on the power supply and record the voltages and output current for a range of input currents determined by the variable resistor

Safety and notes:

-As transformers increase voltage use a low input voltage to keep it at a safe voltage

-The formulas won't quite work as the transformer is not 100% effcient

-Using a laminated core reduces energy loss by eddy currents

-Using low resistance thick copper wire reduces energy lost due to wire resistance

-Using a magnetically soft material reduces energy lost magnetising and demagnetising the core

-Making the coils tighter increases the magnetic flux generated by the primary coil

11.1: Techniques and procedures used to investigate transformers (calculations):

-For the turn ratios, divide the number of turns on the secondary coil (Ns) by the number on the primary coil (Np)

-Calculate the ratio of voltage across the secondary coil (Vs) to voltage across the primary (Vp)

-It should be observed that Ns/Np = Vs/Vp

-It should also be observed that Ns/Np = Ip/Is

-The efficiency of the transformer can be found using

efficiency = IsVs/IpVp

11.2: Determining the specific heat capacity of a material (method):

-Calibrate a top pan balance and measure the mass of an aluminium block

-Insert the thermometer and immersion heater into the block and insulate the block on all sides with cloth, cardboard or another insulator on hand

-Connect the immersion heater to a power supply, ammeter and voltmeter

-Before switching on the power supply, record the temperature of the block with the thermometer

-Switch on the power supply and simultaneously start the stopwatch

-Record the voltage on the voltmeter, current on the ammeter and temperature of the aluminium block every 30s for 5 minutes

-After 5 minutes, turn off the power supply

-Measure the highest temperature reached by the block, which may be a little while after switching off the power supply

Safety and notes:

-The immersion heater can get extremely hot, therefore it must be fully submerged in the aluminium block

-The aluminium block should be insulated to prevent any burns

-The calculated specific heat capacity may be higher than the actual value due to energy losses to the environment, i.e: resistance in the wire, heat loss to the surroundings

-The immersion heater should be touching the aluminium block to transfer heat easily

11.2: Determining the specific heat capacity of a material (calculations):

-Calculate the power for every value of time

-Calculate the work done by the heater for every value of time

-Find the cumulative work done by the heater

-Draw a table of cumulative energy transferred against the recorded temperature of the block at that time interval

-Use the table to plot a graph of cumulative energy against temperature

-Draw a line of best fit, which should be a straight line through the origin

-The line of best fit will have gradient mc

-The specific heat capacity (c) can be calculated by dividing the gradient by the mass of the block (m)

11.3: Determining the uniform magnetic flux density between two poles of a magnet using a current-carrying wire and digital balance (method):

-Set up the wire so it is taught between the faces of the magnets and both the wire and magnets are on top of the balance

-The ammeter and power pack should be part of the complete circuit

-With no current flowing, zero the balance

-Change the supply voltage so that the current, measured on the ammeter, flowing through the wire is 6.0A

-Record the reading on the mass balance

-Repeat the steps and readings, decreasing the current by 1.0A each time until it is 1.0A

-Find the second set of results by repeating the experiment

-Using a ruler, measure the length of the magnadur magnets, L, in metres

-This gives the length of wire in the magnetic field

Safety and notes:

-When using magnets, students with pacemakers should not be near as they can interfere with the pacemaker's function

11.3: Determining the uniform magnetic flux density between two poles of a magnet using a current-carrying wire and digital balance (calculations):

-Find the mean reading on the mass balance (m) for each current (I)

-Plot a graph of the mean m against I

-Draw a line of best fit through the points forming a straight line graph through the origin and calculate the gradient

-The force on the wire is F = BIL

-This is the force found from the zeroed balance reading where F is the weight mg in N

-The gradient of the graph is m/I

-Multiply the gradient by g/L to get the magnetic field strength B of the magnets

-Divide this by 2 to get the magnetic field strength per magnet